Catheters are used as a means for delivering diagnostic or therapeutic agents to target sites within the human body that may be accessed through the circulatory system or through other systemic passageways. For example, in angiography, catheters may be used to deliver a radio-opaque agent to a target site within a blood vessel to allow radiographic viewing of the vessel and of the blood flow characteristics near the agent's release site. For the treatment of localized disease, such as a solid tumor, catheters are used to deliver a therapeutic agent to a target site within the tumor at a relatively high concentration with minimum overall side effects. Methods for producing localized vaso-occlusion in target tissue regions, by catheter injection of a vaso-occlusive agent, have also been described (U.S. Pat. No. 4,708,718 for "Hyperthermic Treatment of Tumors").
U.S. Pat. No. 4,739,768 describes a catheter having a guide wire. The catheter may be guided from an external body access site such as through the femoral artery, to an internal tissue site. The catheter progresses through a tortuous path of at least about 5 cm through vessels of less than about 3 mm inner diameter. The catheter has a relatively stiff segment dimensioned to track the wire from the access site to a region adjacent the internal tissue, and a relatively flexible remote segment dimensioned to track the wire along the tortuous path within the soft tissue. In a method for injecting a fluid into a tortuous path site, the guide wire and catheter are moved as a unit to a position adjacent the target tissue. The wire is then advanced ahead of the catheter along the tortuous path within the tissue. The catheter then tracks the wire to move along the wire's path. Once the tip of the catheter reaches the chosen site, the guide wire is removed and the selected treatment or diagnostic fluid is delivered to the target site.
Although an open catheter lumen is an effective way of delivering relatively large amounts of fluid to a selected vascular site, often it is the situation that controlled amounts of fluid must instead be delivered there. For instance, in treating certain cancerous tumors with a catheter delivering chemotherapeutic agents into the vasculature traversing the tumor, small amounts of the agent desirably would be delivered at a low rate equally over a substantial distance within the tumor.
One device for delivering controlled amounts of therapeutic or diagnostic agents to vascular sites is found in U.S. patent application No. 07/948,720, filed Sep. 27, 1992, now pending entitled "Perfusion Catheter System". This device utilizes a perfusion coil situated at the distal end of the fluid supply catheter. The fluid is introduced through the catheter lumen, through the perfusion coil, and exits through spaces found between the respective coil windings. The fluid exit rate may be actively varied by adjusting the spacing between the coil windings.
Another device suitable for delivering controllable amounts of a fluid to a selected vascular site is found in U.S. patent application No. 07/954,669, filed Sep. 30, 1992, now pending entitled "Drug Delivery Catheter With an Atraumatic Drug Delivery Tip". In this device, the fluid is delivered from the catheter lumen into the vasculature using a set of sideholes in the tip. These sideholes are of a varying size.
One variation of the inventive fluid delivery device discussed below involves the use of a regularly woven tube in which selected strands are omitted from the weave to provide fluid flow through the resulting holes created at the junction of the various strand omissions.
Other surgical or medical devices have used woven or filament containing tubes for a variety of reasons.
For instance, U.S. Pat. No. 4,767,400, to Miller et al., shows a ventricular catheter having a distal portion which is reasonably porous. The porous portion is generally formed by extruding a fiber forming polymer and winding it directly onto a mandrel. The resulting porous portion is made up of several layers of filament but cannot be characterized as being woven. The porous tip is used as a drain for removing excess cerebral spinal fluid (CSF) from a ventricle of the brain. The CSF is drained via a nonporous tubing into a vein terminating in the right atrium of the heart.
Another hydrocephalus shunt is shown in U.S. Pat. No. 4,377,169, issued Mar. 22, 1983, to Banks. This device uses a series of micro-tubes which are formed into a cylinder by mounting them about the peripheral surface of that mandrel. The tubes are then perforated using an ion beam sputter etch technique. The tubes then carry the excess CSF from the cerebral ventricles to other areas in the body.
Another porous surgical drainage tube utilizing, in this case, a metal coil is shown in U.S. Pat. No. 399,540, issued Mar. 12, 1889, to Lee et al.
The use of multi-layer materials involving filamentary layers is shown in U.S. Pat. Nos. 5,176,661, to Evard et al. and in 5,178,158 issued Jan. 12, 1993, to de Toledo. The Evard et al. reference suggests the use of wound tubular resin impregnated fibrous coverings on vascular catheters which coverings are not necessarily porous. de Toledo suggests the use of multi-filar coils having polyamide coverings thereover. Again, these tubing components are not used to exude fluid from the catheter into the body lumen except by a flow through the open end of the lumen.
Finally, several devices for allowing introduction of liquid into a body lumen or withdrawal of fluid from that body cavity are shown in U.S. Pat. No. 4,717,387, to Inoue et al., showing a Teflon frit for flushing an area with a physiological saline solution to allow visual inspection using the catheter; 4,798,598, issued Jan. 17, 1989, to Bonello et al. having a coil placed on the end of a catheter assembly through which various fluids may be introduced into the body; and 4,953,553, issued Sep. 4, 1990, to Tremulis which shows the use of perforations in a hollow guide wire suitable for monitoring pressure in a body lumen.
The present invention is a catheter assembly useful for the delivery of diagnostic or therapeutic agents to regions of the human body often accessible through systems of passageways, e.g., the vasculature and genito-urinary system. In particular, it may be used to diagnose or to treat intravascular occlusions that result from embolus or thrombus formation. The invention also includes a process for delivering fluids to those regions by use of the inventive catheter and perfusion tip.